Powerline communication systems, often called powerline carrier communication system, are method for enabling systems to carry data on a conductor that is also used for electric power transmission, such as a conventional 117 volt AC line, a 230 volt AC line (such as used in Europe), a 100 volt AC line (such as used in Japan), a 277 volt AC line (such as used in certain commercial applications in the United States) or a 347 volt AC line (such as used in certain commercial applications in the Canada). There are many different ways to communicate on a powerline, but ultimately all communication is done by impressing a modulated carrier signal onto the system power conductors together with the 117 volt AC power signal and separating the power signal and the communications signals at a receiving point. While powerline communication applications are commonly seen in the utility meter reading and home automation markets, for example, for a number of reasons they are essentially nonexistent in architectural solid state lighting systems.
Among the problems that are hindering the adoption of solid state lighting systems, that is, light emitting diode (LED) lighting systems, and especially white light lighting systems, is the question of control of the light level output of LED lighting systems, that is, dimming control, which is much more complex than in the case of conventional lighting systems because of the greater electrical complexity of the LED lighting fixtures. For example, two of the common industry standard methods for dimming control of lighting systems are 0-10V dimmers and the Digital Array Lighting Interface (DALI), both of which provide digital control of the power output of lighting systems. Both of these methods are effective, but require the provision of control wiring separate from the conventional AC power lines. The addition of 0-10V dimmers or DALI to a lighting installation thus generally requires the retrofitting of any proposed installation site with the necessary control wiring, which typically requires ripping out existing wiring and the addition of new control wiring. The addition of convention dimming controls, such as 0-10V dimmers or DALI to a lighting installation thereby often imposes significant additional costs as well as additional time to accomplish the installation of the control wiring and controls.
There are existing dimming technologies used for traditional lighting sources which do not require extra communication wires. While there are many, two of the most popular are TRIAC (triode for alternating current) dimmer and Electronic Low Voltage (ELV) dimming. Both “phase chop” the AC signal, making less AC power available for the traditional light sources, hence causing the traditional light sources to provide less light output. These dimming technologies have been adapted to solid state lighting fixtures, however, since they are analog in nature, they are not an ideal solution due to the strictly digital nature of LEDs. There are two distinct disadvantages to incorporating TRIAC or ELV on the LED fixture. For example, there is an added cost associated with adding analog circuitry in order to transmit TRIAC or ELV dimming signals over a power line and to convert the analog signals to digital signals suitable for controlling LED fixtures. In addition, the addition of such specific purpose circuitry commits the LED fixture manufacturer to one technology, thus limiting the ability of the manufacturer to adapt to other dimming technologies that may be required in different applications and installations.
The present invention provides a solution to the above noted as well as other related problems associated with the prior art.